MiniSKiiPIPM面向中等功率应用的先进模块架构

电力电子技术可以帮助提高能源效率和节约大量能源,尤其是在中等功率应用市场中。得益于其高集成度和简单的组装,本文所介绍的600V智能IGBT功率模块能够促进电力电子的应用。该模块的特点在于其基于双极性电平转换器的先进概念。因此,所集成SOI驱动器不受参考电压变化的影响,输出功率高达15kW,从而提高了在应用中的可靠性。     

Subacute myocardial infarction: assessment by STIR T2-weighted MR imaging in comparison to regional function

Purpose Increased T2 signal intensity (SI) can be regularly observed in myocardial infarction. However, there are controversial reports about the relationship of elevated T2 SI to myocardial viability and some authors propose that high T2 SI serves as a sign of irreversible myocardial injury. This study investigates increased T2 SI compared to myocardial function in patients with reperfused subacute myocardial infarction. Preserved function was used as criterion for viability. Methods Ten healthy volunteers and 17 patients with myocardial infarction and patent inlarct related coronary artery were examined on a 1.5 T Magnetom Vision system (Siemens). For T2-weighted MR imaging a breath-hold STIR sequence with dark-blood preparation was used. Cine FLASH 2D imaging was applied to assess myocardial function. Signal-to-noise (S/N) in STIR T2 images was measured in normal and infarcted regions and subsequently identified by two independent observers. Based on a 20 segment model of the left ventricle findings were compared to regional myocardial function. Results Elevated STIR T2 SI was found in all 17 patients and observed in 27% (204/754) of segments. S/N of normal myocardium was 5.1 ±0.7 in volunteers and 4.9 ± 0.8 in patients(P=NS). Infarcted myocardium presented with significantly-increased S/N 12.8 ± 1.9 (P < 0.0001). Significant transmural elevation of T2 SI was noted in 32% of segments with preserved systolic function. Conclusion Increased STIR T2 SI can be observed transmurally in post-ischemic myocardial regions with preserved function. It therefore cannot be used as an exclusive marker for the non-viable region.     

Nanocomposites of polypropylene/titanate nanotubes: morphology,nucleation effects of nanoparticles and properties

High-quality titanate nanotubes (TiNT) were mixed with modified polypropylene (PP*) by a batch melt-mixing procedure. To improve compatibility between the nanofiller and the matrix, polypropylene (PP) was modified by electron beam irradiation. Effects of TiNT nanoparticles on crystallization, mechanical, thermal and rheological properties of the modified polypropylene were studied and compared with the analogous systems filled with commercial micro- (mTiO₂) and nano- (nTiO₂) titanium dioxide particles. Nucleation effects of the TiO₂-based fillers on PP* crystallization were investigated in detail. The microstructure of the PP*/TiNT nanocomposites shows well-dispersed TiNT sparse aggregates (clouds), penetrated by the polymer. A large-scale structure in the nanocomposite melts confirmed also rheology. In comparison to the matrix characteristics, the stiffness and microhardness of the TiNT nanocomposites increase by 27 and 33 %, respectively. The enhancement in mechanical properties demonstrates that the quality titanate nanotubes can be used as an efficient filler in non-polar polymers using the polymers modified by irradiation. In the case of the nanocomposites containing nTiO₂-anatase particles, the increase in these mechanical characteristics is lower. The investigated changes in the rate of crystallization indicate a marked nucleation effect of the nanotubes. The crystallization kinetics data, processed by the Avrami equation, suggest 3-dimensional crystal growth in the polypropylene matrix. The observed improvement in mechanical properties of the TiNT nanocomposites is induced not only by the nanofiller reinforcement but also by the changes of supermolecular structure of the polymer matrix due to nucleated crystallization.     

Differentiation between proteolytic activation and autocatalytic conversion of human prothrombin. Activation of recombinant human prothrombin and recombinant D419N-prothrombin by snake venoms from Echis carinatus and Oxyuranus scutellatus

Recombinant human prothrombin (r-prothrombin) and recombinantmutant prothrombin with active site Asp419 substituted by Asn(D419N-prothrombin) were expressed in recombinant CHO cells,isolated and purified from the fermentation supernatant. Ther-Prothrombin and D419N-prothrombm were digested by both Echiscarinatus venom and Oxyuranus scutellatus venom. Prior to, duringand after activation, generation of thrombin activity and theproteolytic degradation of the prothrombin polypeptide chainwere analysed. Owing to the recombinant preparation and inactivityof D419N-prothrombin and its activation products, the proteolyticaction of E.carinatus and O.scutellatus venoms could be studiedwithout addition of thrombin inhibitor, without interferencefrom autocatalytic digestion of prothrombin and in the absenceof any other blood coagulation protease. The comparison betweenthe activation of r-prothrombin and D419N-prothrombin by snakevenoms permitted differentiation between proteolytic activationand autocatalytic conversion of prothrombin. Incubation of D419N-prothrombinwith E.carinatus venom resulted in the generation of stableD419N-meizothrombin by hydrolysis of the peptide bond Arg320-Ile321.By contrast, O.scutellatus venom exhibited activity towardspeptide bonds Arg320-Ile321 and Arg271-Thr272 and lower activitytowards peptide bond Arg155-Ser156, thus converting D419-prothrombininto D419N-thrombin and also liberating Fragment-1, Fragment-2and Fragment-1/2 activation peptide. Activation of r-prothrombinby E.carintitus and O.scutellatus venoms demonstrated the autocatalyticpotential of prothrombin-derived molecules and indicated thatmeizothrombin hydrolysed the cleavage between Fragment-2 andthrombin A-chain in the meizothrombin molecule, but not in prothrombin,preferentially at position Arg284-Thr285. By contrast, bothmeizothrombin and thrombin exhibited no detectable activitytowards peptide bond Arg320-Ile321 between thrombin A- and B-chain,although this site exhibits the optimum sequence for thrombincleavage.     

Potenziale und Herausforderungen in der Implementierung der organophilen Nanofiltration in der Spezialchemie

Organic solvent nanofiltration (OSN) is a suitable tool for process intensification. For specialty chemicals production within a multi‐purpose environment, there are some specific concerns regarding membranes and equipment design that have to be considered. Process development for OSN to date is hampered by a lack of system characteristics and detailed transport models. Here, we present a systematic investigation with different membrane materials and solvents in order to define guidelines for a fast membrane selection.     

Economic Assessment of the Hydrogenation of CO2 to Liquid Fuels and Petrochemical Feedstock

To remove high concentrations of CO₂ from the off‐gas of coal‐driven power plants, a new process was proposed. The catalytic hydrogenation of the CO₂ leads to the production of C₂ – C₄ (petrochemical feedstock) and liquid C₅₊ hydrocarbons (fuel). Thus, environmentally harmful CO₂ may be converted sustainably to useful products. On the basis of a process flow sheet, the costs for processing the CO₂ are estimated for different plant sizes. The price of hydrogen contributes significantly to the overall production costs. Further price reductions may be achieved by final engineering optimization of the process as a whole and specific unit operations.     

Cell Types and Synapses Expressing the SNARE Complex Regulating Proteins Complexin 1 and Complexin 2 in Mammalian Retina

Complexins (Cplxs) 1 to 4 are components of the presynaptic compartment of chemical synapses where they regulate important steps in synaptic vesicle exocytosis. In the retina, all four Cplxs are present, and while we know a lot about Cplxs 3 and 4, little is known about Cplxs 1 and 2. Here, we performed in situ hybridization experiments and bioinformatics and exploited Cplx 1 and Cplx 2 single-knockout mice combined with immunocytochemistry and light microscopy to characterize in detail the cell type and synapse-specific distribution of Cplx 1 and Cplx 2. We found that Cplx 2 and not Cplx 1 is the main isoform expressed in normal and displaced amacrine cells and ganglion cells in mouse retinae and that amacrine cells seem to operate with a single Cplx isoform at their conventional chemical synapses. Surprising was the finding that retinal function, determined with electroretinographic recordings, was altered in Cplx 1 but not Cplx 2 single-knockout mice. In summary, the results provide an important basis for future studies on the function of Cplxs 1 and 2 in the processing of visual signals in the mammalian retina.     

Inhibitory effect of polyphenol-rich extracts of jute leaf (Corchorus olitorius) on key enzyme linked to type 2 diabetes (α-amylase and α-glucosidase) and hypertension (angiotensin I converting) in vitro

Corchorus olitorius leaf is consumed in various parts of the world as leafy vegetable and folk remedy for the management of some degenerative diseases with dearth of information on its biochemical rationale. Therefore, this study sought to characterize the inhibitory action of polyphenol-rich extracts (free and bound) of C. olitorius on α-amylase, α-glucosidase and angiotensin I converting enzyme (ACE), as well as to identify the phenolic compound responsible for these activities. Our findings revealed that the extracts inhibited α-amylase and α-glucosidase (12.5–50.0 μg/mL), and ACE (10.0–50.0 μg/mL) in dose-dependently with free extracts having significantly (P < 0.05) higher α-amylase (17.5 μg/mL), α-glucosidase (11.4 μg/mL) and ACE (15.7 μg/mL) inhibitory activities as revealed by the IC₅₀. Reversed-phase HPLC analysis of the extracts revealed chlorogenic acid (7.5 mg/100 g) and isorhamnetin (51.1 mg/100 g) as the main phenolics in the free extract and caffeic acid (58.1 mg/100 g) in the bound extract. Therefore, the enzyme inhibitory activity of C. olitorius extracts may be attributed to the presence of caffeic acid, chlorogenic acid and isorhamnetin, thus justifying its use in folklore for the management of diabetes and hypertension.